Resistance unit



March 13, 1928. ,662,771

G. H. wHlTTlNGl-IAM RESISTANCE UNIT Filed May 8, 1926 Patented Mar. 13, 1928.

UNITED STATESv PATENT OFFICE.

GEORGE E. WHITTINGIIAM, OF BALTIMORE, MARYLAND, ASSIGNOR TO MONITOR CONTROLLER COMPANY, OF BALTIMORE, MARYLAND, A CORPORATION .OF MARY- LAND.

RESISTANCE UNIT.

Application med nay s, 1926. serial No. 167,613.

This invention relates to resistance units composed` of wire coils wound on bodles of refractory material, such as porcelain. Porcelain is desirable as a support for the windings because of its high heat-resisting and insulating properties; but ditliculty is encountered in satisfactorily securing terminals and other connectors to the porcelain because of its hard and brittle character. The purpose of the present invention is to provide a resistance unit in which the terminals and other connectorscan be secured at any desired-points on the unit, the securing means being the coil itself. In carrying out the invention, I provide a'metal supporting bar, having an insulating covering composed ofv refractory material, this covering having coil-supporting ltoothed ribs extending longitudinally of the bar and having spaced pockets between the ribs. The terminals or other connecting devices are formed with 'parts adapted to fit interchangeably in these pockets, and the resistance coil, wound over the toot-hed ribs and pockets, serves as a means for holding the connectors in place upon the covering.

In the accompanying drawing,

Fig. 1 is a side elevation of ares1stance unit, partly in section and partly broken away;

Fig. 2 is an end elevation of the sume, looking from left to right in Fig. 1, the insulating coveringbeing partl in section;

Fig. 3 is a top plan view o the left hand end portion of the unit shown in Fig. 1, with the wires partly removed;

Fig. l4 is a section on the line 4 4 of Fig. 1;

Y Fig. 5 is a perspective view of one of the terminals shown in Fig. 1; and

Fig. 6 is a similar view of the tap shown in Fig. 1.

Referring to the drawing, a represents a flat metal supporting bar, having heads 1 and 2 at its ends which are wider than the bar, and the bar, between the heads, has a covering b of-refractory material, preferably porcelain. This covering is composed of a lurality of relatively short pieces of porceihin, all alike in size and form. Thus, in Fig. 1, two pieces 3 and 4 are shown on the upper half of the bar and similar pieces 3* and 4 are shown on the lower half of the bar. Each piece of porcelain has a slot or channel 5, as shown in Fig. 4, and these slots tit over the bar, as shown in said figure, so that the opposing sections, as 4 and 4, cover the bar and interlock with it. Each section has several ribs 6, 7, and 8., vwith teeth 6a, 7a, and 8, between which the wire coil` 9 is wound. In the channeled portions of the insulators, between the ribs, are formed angular pockets 10, spaced short distances apart longitudinally of the bar. The intervening parts 11, between the pockets, )om the adjacent ribs and strengthen the ribs. The wire 9 is wound over the ribs, between the teeth, and spans the channels which afford room for the circulation of air around the wire.

With wire wound units of this character, in,which refractory material is used as an insulator, ditliculty is experienced in securlng connectors, such as terminals and taps, to the unit, because of the hard and brittle nature of the material. To overcome this dif. ticulty, I provide the pockets in the insulator, and the connectors are provided with bases which fit into these. pockets, and these bases are held within the pocket-s by the coil whlch is wound about the insulator. Thus, the unit shown inv Fig. 1 is provided with two terminals t, each consisting of a Sheet metal strip having a body portion 12, to

which the. wires may be connected, a foot 13,

turned over at right angles to the partk 12,

and two forked arms 14, inclined down-- wardly from opposite sides of the foot and fitting into the pockets 10 at oppositesides of the rib 7. The foot 13 is shown with an upwardly turned end 13, as a convenience for retaining the wires when the coil is wound, but this end. may be omitted. When the coil is to be wound, a terminal is placed on the insulator, as shown in the drawing, with its foot portion resting on a rib and the forked arms extending into the adjacent pockets, the terminal thus straddling` the rib. The coil is then wound on to the unit and over the foot of the terminal, thus binding the terminal to the insulator. The foot `tbns connected to the ooit.

Itbereon composed ot retrectornv non turns or convointions ot .tbe coii vvbicb onse over tbe teet ot tbe terrninois eiectriceiiy connect the iotter with tbe Wire.. Tirocinii convoiutions 15 ot the coii also poss over feet ot the terminals end ere bent around tbe upright portions i2 and secured to tbe ictter by demping screws liti.. 1 v

The ocirets spaced sbort distances eport9 throughout tbe iengtb ottbe insnintor7 ere provided in order tbot tops moy be connected to tbe coii et any 'desired pointsin its iengtb. @ne ot these tops is shorvn nt in winding tbe coii, o nut t7., termed to tit intdony one ot tbe pockets, is pieccd in o boeket9 ot o point on tbe coii vvbere it mcy be desired to connect o tcp Wire, end tbe vvire is vvonnd over this nut., The pocirets nre varranged vvitb respect to the teetb tbe ribs it so tiret two convoutions ot tbe coii vviit entend over eecb pocket. After tbe vvire bes been Wound, the tbreoded end i8 ot o binding post i8 is inserted between tbe convointions Wbicb poss over tbe nut tif ond into tbe not, end when this binding post is screvved down into tbe nutsthe two convo intions ot vvire vviit be gripped between tbe nntnnd tbe binding post. Thus, e goed eiectricot connection vviii be inode between tbe coil ond tbe binding post and tbe tot ter vviti be beid tiriniy in position on tbe unit. tny desired number ot' tops tney be The tops and terminois nre sbotvn in the drovving mount ed on tbe ripper boit ot tbe insuietor but they non v be connected to tbe iov-ver bott9 desireds os tbe iotver ports ot tbe insnietor ore tbe some os tbe upper ports;

t A resistnnce unit coni rising o nietni supporting bor9 on insu oting covering thereon composed oii ret'rectory nonterini9 seid covering iter/'ing coii supporting toothed ribs extending iongitndinniiy ot tbe bor pockets between tbe ribs e, connector notim ing o port tting vvitiiin one ot scid "occirets, ond e vvire coit Wound about covering end over port,

2, t. resistance nnit comprising supporting bcn en insnieting cover scid covering bnr/'ing coit supporting te i ribs extending longitndinniigr ot the boring e series ot pockets between edi? 'a ribs, n connector boving n loert a nt interchangeably in seid pockets ond ntting vlitbin one ot scid pockets9 ond o Wire coii `Wound over seid ribs and port. f

3. A resistonce unit comprising e inetei supporting bonen insniating covering tbereon composed ot refractory materiel, seid covering ber/ing coii supporting toothed ribs extending iongitudinotiy ot tbe bor ond boring o series ot nngnlnr pockets between ndjscent ribs, o connector bor/ing on eng-nn ier port indebted to tit intercbongenbiy in.`

jacent cbcnneisf, ond n vvire coii Wound around seid ribs end soidbosc ond securing the connector to tbe covering 5. A resistentie unit comprising e nietoi supporting bor, nn insulating covering thereon composed ot retrnctory inoterioi9 seid covering having n pinrniity ot tootbed ribs ond intervening cbonneis extending iongin tndineiiy ot tbe bor ond lbeving jpocirets spoced eport in scid cbonneis9 e connector boring n bose resting on one ot seid ribs bor/ing iorired orrns projecting into 'ed-v ilecent pockets9 end c vvire coii Wound oround seid ribs ond bose ond securing tbe connector to tbe covering.

d, it resistence nnit comprising o nietot supporting bnr9 eninsnieting covering thereon composed of refractory moteriei, scid covering boiling e piuroiity of toothedy ribs series ot spaced pockets extendingy iongitudineib/'v ot tbe covering between odio cent ribs n connector comprising o bese and binding post, tbe tornooin adopted to tit intercbcngeobiy in seid pocietsaend fitting in one ot soi-d lnocirets, ovvirecoii Wound over ribs joocirets end bese, ond scid bin-ding boving o tbreoded connection with scid bose ond demping tbe totter to tice coii.,

iin testinionj,7 'wbercot ii berennto my sinnctnro bese resting on one ot scid ribse-nd iorired titi 

